background noise removal in matlab

[akshay15]

hi i am working on real time audio signal taken from the microphone attached to the sound card and reading the data in matlab and analysing the frequency components in matlab .but my signal range i.e the audio range as we know is from 150hz to 3000hz and the problem is that the background noise is also in that range so how do i remove this type of noise from surrounding ,, plz reply asap.. itz related to my project .thanks in advance..

 

[andre_luis]

If would possible attach another microphone at another card, could record just the noise, and then subtract one from other : (Voice+Noise)-(Noise)=(Voice).


+++

 

[akshay15]

hey nice idea but i don't have the provision for it my mic is placed on the bot and is coonected to laptop soundcard.so do suggest some new idea .

 

[lebesgue]

Assuming that the noise is additive .Take Fourier transform of the signal and plot the magnitude spectrum. Find the band of frequency over which the noise exists. The information signal would naturally have peaks near a band of frequencies as you can note. The noise would mostly exist in the floor of the spectra. Filter out the signal by defining an appropriate filter defining the cutoff frequencies. For real time data acquisition,adaptive filtering can be used.

 

[guitarguy12387]

You can use a wiener filter if you want to get more advanced:
WIENER FILTERING